Generally, when manufacturing a semiconductor device, a process for forming various thin films, a reforming process, an oxidation/diffusion process, an annealing process, an etching process and the like are sequentially and repeatedly carried out on a semiconductor wafer. For example, multilayer thin films can be formed on a semiconductor wafer.
For example, in a single wafer processing system, a plurality of process chambers is connected in common to a single transfer chamber in order to continuously perform the above various processes, thereby forming a so-called cluster processing apparatus. Further, a semiconductor wafer is transferred, so to speak, from one processing space to another, thereby sequentially and efficiently performing necessary processes in respective process chambers.
An example of a conventional processing system including such a cluster processing apparatus will be described with reference to FIG. 7.
As shown in FIG. 7, the processing system has a vacuum processing apparatus, wherein four process chambers 104A to 104D are connected to a common transfer chamber 102 of, e.g., a hexagon shape via gate valves 106, respectively. Further, a rectangular shaped loading transfer chamber 110 is connected to the common transfer chamber 102 via two load lock chambers 108A and 108B.
Gate valves 106 are interposed in coupling portions between the load lock chambers 108A and 108B and the common transfer chamber 102 and in coupling portions between the load lock chambers 108A and 108B and the loading transfer chamber 110, respectively. Further, coupled to the loading transfer chamber 110 are, e.g., three introduction ports 112 for mounting a cassette capable of accommodating plural sheets of semiconductor wafers and an orienter 114 for performing a position alignment of a semiconductor wafer W.
In addition, installed in the loading transfer chamber 110 is a loading carrying mechanism 116 which has two picks 116A and 116B for supporting the semiconductor wafer W and is contractible, extensible, revolvable, straightly movable vertically and horizontally. Further, disposed in the common transfer chamber 102 is a carrying mechanism 118 which has two picks 118A and 118B for supporting the semiconductor wafer W and is contractible, extensible and revolvable.
Herein, supposing that processes are performed on the semiconductor wafer W in respective process chambers 104A to 104D in that order, the semiconductor wafer W is transferred from the introduction port 112 as indicated by arrows. That is, the wafer W is transferred from, e.g., the central introduction port 112 to the orienter 114 while being supported by the pick 116A or 116B of the loading carrying mechanism 116. The position of the wafer W is aligned in the orienter 114 and then supported again by the pick 116A or 116B to be transferred into any one of the load lock chambers, e.g., the load lock chamber 108A. The wafer W transferred into the load lock chamber 108A is sequentially transferred from one chamber to another to pass through the respective process chambers 104A to 104D in that order by the pick 118A or 118B of the carrying mechanism 118 in the common transfer chamber 102. Necessary processes are carried out on the wafer W in the respective process chambers 104A to 104D. Then, the wafer W on which various processes have been completely performed is unloaded into the loading transfer chamber 110 via any one of the load lock chambers, e.g., the other load lock chamber 108B in this case and, thereafter, returns to the original introduction port 112.
In the respective carrying mechanisms 116 and 118, one of two picks is kept empty to improve a throughput. A wafer already mounted or accommodated in a place is picked up by an empty pick to thereby make the place empty. Then, a wafer supported by the other pick is mounted or accommodated in the above empty place. Accordingly, the wafers are smoothly exchanged, thereby improving the throughput.
Furthermore, as a conventional technique for preventing cross contamination, there is a processing system including a plurality of process chambers and a carrying mechanism having a plurality of picks being assigned to each process chamber (see, for example, pages 3 and 4, FIGS. 1 and 2 of Japanese Patent Laid-open Application No. H7-122612). In accordance with the technique, contaminants generated in any step (process chamber) do not affect other steps even though a wafer is transferred between process chambers.